fix: resolve critical pagination bugs and add comprehensive testing

- Fix off-by-one error in pagination loop (< to <=) that prevented fetching last page
- Add Math.ceil() to maxNumberOfPages calculation for proper limit handling
- Replace hardcoded 2000 limit with configurable getMaxArtifactListCount()
- Add pagination test for multi-page artifact listing
- Add environment variable test for ACTIONS_ARTIFACT_MAX_ARTIFACT_COUNT
- Add comprehensive test coverage for getMaxArtifactListCount() function

Fixes compound bug where pagination and limit logic capped results at 900 artifacts instead of intended 1000.

packages/artifact/src/internal/find/list-artifacts.ts

@@ -9,12 +9,12 @@ import {retry} from '@octokit/plugin-retry'
 import {OctokitOptions} from '@octokit/core/dist-types/types'
 import {internalArtifactTwirpClient} from '../shared/artifact-twirp-client'
 import {getBackendIdsFromToken} from '../shared/util'
+import {getMaxArtifactListCount} from '../shared/config'
 import {ListArtifactsRequest, Timestamp} from '../../generated'
 
-// Limiting to 2000 for perf reasons
-const maximumArtifactCount = 2000
+const maximumArtifactCount = getMaxArtifactListCount()
 const paginationCount = 100
-const maxNumberOfPages = maximumArtifactCount / paginationCount
+const maxNumberOfPages = Math.ceil(maximumArtifactCount / paginationCount)
 
 export async function listArtifactsPublic(
   workflowRunId: number,
@@ -81,7 +81,7 @@ export async function listArtifactsPublic(
   // Iterate over any remaining pages
   for (
     currentPageNumber;
-    currentPageNumber < numberOfPages;
+    currentPageNumber <= numberOfPages;
     currentPageNumber++
   ) {
     debug(`Fetching page ${currentPageNumber} of artifact list`)

packages/artifact/src/internal/shared/config.ts

@@ -97,3 +97,22 @@ export function getUploadChunkTimeout(): number {
 
   return timeout
 }
+
+// This value can be changed with ACTIONS_ARTIFACT_MAX_ARTIFACT_COUNT variable.
+// Defaults to 1000 as a safeguard for rate limiting.
+export function getMaxArtifactListCount(): number {
+  const maxCountVar = process.env['ACTIONS_ARTIFACT_MAX_ARTIFACT_COUNT']
+  if (!maxCountVar) {
+    return 1000
+  }
+
+  const maxCount = parseInt(maxCountVar)
+  if (isNaN(maxCount) || maxCount < 1) {
+    throw new Error(
+      'Invalid value set for ACTIONS_ARTIFACT_MAX_ARTIFACT_COUNT env variable'
+    )
+  }
+
+  return maxCount
+}
+